Here are the tried and tested tips to find long-tail keywords for your website:1. Think how will you search if you were the user (Determine Searcher's Intent)2. Use Google Keyword Planner3. Look up to Google's Keyword Suggestions and LSI's you see on the bottom of the SERP4. Make use of tools like BuzzSumo, Keywordtool.io, Answer the Public & such more